The present invention relates to an apparatus for manufacturing bulbs capable of solely performing both sealing between the bulb body and mount and tipping-off of the exhaust tube of the mount.
In general, a method for manufacturing a bulb, e.g., a fluorescent lamp, includes a sealing process for sealing a flare portion of a mount to the opening edge of a tubular bulb body, and an exhaust process for exhausting in the bulb body through an exhaust tube extending from a mount, introducing mercury and inert gas into the bulb through the exhaust tube, and then tipping-off the exhaust tube. Recently, there has been developed a manufacturing apparatus capable of solely executing both those processes in succession. This apparatus includes a head body and a mount holder attached to the head body to hold the mount of the bulb. The mount holder is in the form of a cylinder with a hole in which the exhaust tube of the mount is to be inserted. Fitted in the hole of the mount holder, moreover, is a cylindrical tipping-off burner for tipping-off the exhaust tube. The apparatus further includes a sealing burner arranged around the mount holder for sealing the flare portion of the mount and the opening edge of the bulb body, and a butting plate so arranged around the mount holder as to be able to reciprocate along the axis of the mount holder for pressing and securely sealing the flare portion and the opening edge of the bulb body. Furthermore, the apparatus includes an exhaust head located adjacent and opposite to the mount holder for airtightly chucking the extended end portion of the exhaust tube, exhausting in the bulb through the exhaust tube and introducing inert gas and mercury into the bulb.
The manufacturing apparatus of the above-mentioned construction is used for manufacturing conventional fluorescent lamps with bulb diameters ranging about from 29 mm to 38 mm. Recently, however, there have been developed lamps with reduced bulb diameters for higher efficiency. When using the aforesaid apparatus for the manufacture of the fluorescent lamps with the reduced bulb diameters, the inside diameter of the butting plate, which is functionally expected to be a little smaller than the outside diameter of the bulb, must be reduced in proportion to the reduction of the bulb diameter. Also, the outside diameter of the mount holder need be reduced correspondingly to the inside diameter of the butting plate. Since the tipping-off burner is fitted in the mount holder and the size of the tipping-off burner is defined, the inside diameter of the mount holder may not be reduced. Accordingly, if the outside diameter of the mount holder is reduced as aforesaid, the wall of the mount holder will extremely be thinned, possibly leading to deterioration of the mount holder in mechanical strength.
The above-mentioned apparatus having the tipping-off burner built in the mount holder, moreover, is complicated in construction to require much labor for assembly and disassembly for maintenance and inspection, for example. Furthermore, in such apparatus, it is hard to observe the operating state of the tipping-off burner from the outside.